The overall goal of the proposed research is to use rich prospective data and state of the art quantitative methods to examine pathways contributing to missed scheduled clinic visits and virologic failure among African Americans (AAs) receiving HIV medical care. Existing data from AA participants enrolled in three sites of the Center for AIDS Research Network of Integrated Clinical Systems (CNICS) (R24 AI067039-1; M. Saag, PI; http://www.cnics.net/index.html) will be used for the proposed study. CNICS is a large and diverse consortium of cohort studies of over 22,000 HIV infected patients receiving ongoing primary HIV care in a clinic setting after 1 January 1995. Selected sites for the proposed work include the University of North Carolina Center for AIDS Research HIV Clinical Cohort (J. Eron, PI), the University of Alabama at Birmingham (UAB) 1917 Clinic Cohort (M. Saag, PI), and the Johns Hopkins HIV Clinical Practice Cohort (R. Moore, PI). The proposed study aims to (1) examine whether availability and use of ancillary services (i.e., case management, alcohol and drug abuse treatment) is associated independently with a lower risk of subsequent HIV virologic failure and assess whether this association is mediated by scheduled appointment attendance; (2) examine whether competing needs (i.e., forgoing medical care due to work or limited funds) are associated independently with an increased risk of subsequent HIV virologic failure and assess whether this association is mediated by scheduled appointment attendance; and (3) examine whether dissatisfaction with the healthcare provider-patient relationship is associated independently with an increased risk of subsequent HIV virologic failure and assess whether this association is mediated by scheduled appointment attendance. For all three aims, marginal structural modified Poisson regression models will be used to estimate total, natural direct, and natural indirect effects of ancillary HIV services, competing needs, and healthcare provider-patient relationships on virologic failure. Indirect effects mediated through scheduled appointment attendance will specifically be explored. Results from the proposed work will identify barriers to care among HIV-infected AAs and inform implementation of targeted interventions at the patient and contextual (e.g., clinic, neighborhood, policy) level to minimize such barriers. Minimizing barriers to care among AAs will in turn reduce substantial and longstanding racial disparities in HIV disease.